1. Field of the Invention
This invention relates generally to appliances for use in medicine, including veterinary medicine; and more particularly to a substance-dispensing appliance for facilitating and enhancing the use of a short-term or indwelling catheter or other tube, or other relatively thin, elongate article employed in therapy.
Various forms of the invention are useful either in insertion or in maintenance--or both--of such an elongate article in a living body. The invention is applicable, for example, to such catheters as the Foley urinary-tract catheter or other urinary catheters, as well as tracheal, cardiac, or central or other venous catheters.
The invention is also suitable for use with tubes that irrigate or drain body cavities such as (without exclusion) the pleural, peritoneal, subarachnoid, intrathecal, subdural and intracraneal cavities--or that are used for special procedures such as evacuation of hematoma. Furthermore our invention is not limited to use with articles having conductive lumens; rather, it can be employed as well with solid rods--either flexible or stiff--that find therapeutic use in medicine.
For illustrative purposes, we shall first discuss at some length the need for our invention in one familiar area. That is the area of catheters which are placed in the urinary tract.
2. Prior Art
A urinary-tract catheter can be used in hospitalized patients, in elderly patients confined to nursing homes, and in outpatients alike, on both a short- and long-term basis. In any case, catheter insertion is most often accomplished manually by a nurse, doctor, medical student or orderly, under various conditions, often hurried. The catheter is supplied sterile but is subject to contamination anytime after it is removed from its sterile wrap. Major problems with urinary-catheter contamination arise in particular at the time of insertion. For a discussion, see Cecil's Textbook of Medicine, seventeenth edition, II:1487, 1985.
Causes of contamination during insertion of a urinary-tract catheter can be multiple. It sometimes happens, for example, that hospital or nursing-home personnel neglect proper aseptic technique and thus transport bacteria, fungus and other infecting organisms from patient to patient.
Improper technique can include failure of medical personnel to wear sterile gloves. Further, medical personnel may unpackage and put on gloves improperly. Personnel also may fail to wear masks on a routine basis, causing contamination of the catheter from the larynx, mouth and nose.
Failure of medical personnel to properly "prepare" (sterilize or drape) a wide enough area of the patient's body can cause contamination if the catheter touches the unsterile area while the catheter is being threaded into the urethral meatus. Contamination can occur during application of aseptic solution to the patient or to the catheter.
A "false passage"--missing the urethral opening during threading--can cause contamination of the catheter on the patient's perineum or anus. A false passage is relatively likely to occur because the catheter is flexible, and therefore difficult to guide into the urethral opening on the first try.
This is especially true for a female patient, whose urethral opening is more difficult to locate than a male's. The insertion process may sometimes have to be started over, thus multiplying the possibilities for contamination and taxing the medical staff member's time, energy and patience.
Problems with catheter contamination are so great, in fact, that urinary-tract catheters are reported to be the major cause of nosocomial (institution-acquired) urinary-tract infections. There is no question that many of these infections could be avoided if catheters could be inserted in a truly aseptic manner.
It has been estimated that 3.6 percent of all patients admitted to hospitals acquire nosocomial urinary-tract infections (Evans, R. Scott, et al., JAMA, vol. 256, 1985). Approximately eighty percent of these infections occur in patients who have undergone some form of instrumentation, usually catheterization (see Cecil's Textbook of Medicine).
The extra time patients spend in hospitals because of infections related to their short-term and indwelling catheters is estimated at five to six days per hospital stay (see Platt, R. et al., "Mortality associated with nosocomial urinary tract infections," New Engl. J. Med. 307:637-642, 1982). The cost of nosocomial urinary-tract infections in hospitals alone is a "staggering 1.8 billion dollars a year" (Rutledge, K. A. and MDonald, H. P., Jr., "The Costs of Treating Simple Nosocomial Urinary Tract Infections," Supplement to Urology, vol. 26:24-26, 1985).
Incidence of urinary-tract infection is also high in outpatients who require indwelling urinary catheters, such as paraplegics and people with chronic urinary obstruction. This problem is discussed by Platt, and also by Edwards, C. D., "The epidemiology of 2056 remote site infections," Ann. Surg. vol. 184, 1976.
Maintenance of urinary catheters is often necessary for paraplegics, as loss of urinary control commonly accompanies their condition. Heretofore such paraplegics have been maintained on virtually constant antibiotic supply, to avoid urinary infection arising from catheterization; even so, their catheters must be changed on a regular basis.
This technique, however, is unhealthy and undesirable as it carries a danger of both tolerance to existing bacteria and bacterial mutation "around" the available antibiotics. Protracted use of each catheter, with little or no antibiotics, could be enjoyed if there were some way to insert and maintain such catheters free of contamination and infection.
There is little question that urinary-tract infections--many of which can be directly attributed to improper insertion technique--lead to increased costs for medication, doctors' time, longer hospitalization, and increased morbidity and mortality.
In nursing homes, such notorious hazards of urinarytract infection have apparently deterred the use of urinary catheters on a broad scale, even though such catheters are well known as a means of alleviating the distress of urinary incontinence. Even with such limited use, seven million nosocomial urinary-tract infections--many due to catheter use--occur per year in patients confined to nursing homes (see Cecil's Textbook of Medicine).
As a result, elderly patients in nursing homes are generally denied the benefits of such catheters. It is therefore reasonable to consider nursing-home costs arising out of the complications of urinary incontinence. Such costs are estimated in the range $0.5 billion to S1.5 billion per year.
These values represent three to eight percent of all nursing-care costs (see Ouslander, J. G. and Kane, R. L. in "The cost of urinary tract incontinence in nursing homes," Med. Care 22:69-79, 1984). Yet, as already suggested, it is generally held that nursing homes would incur greater cost if they put urinary catheters into general use, employing existing catheter-insertion technique.
This discussion makes clear that the need is great for some way to insert and maintain urinary tract catheters, free from the many sources of contamination discussed above. If indwelling urinary-tract catheters could be inserted aseptically--and particularly if they could be maintained free of contamination and infection for long periods after insertion--the favorable results would include great reductions in infection and human suffering, and save millions of dollars in time and costs every year.
The need is not limited to urinary catheters. A like need exists whenever sterile catheters, tubes, or other elongate articles of therapy are inserted under sterile conditions into a living body. Examples include (among others) pacemakers and central lines (catheters or tubes placed into large veins), as well as Swan-Ganz catheters.
Often these must be inserted under emergency conditions in emergency rooms and intensive- and cardiac-care units. In these situations sterility is too easily compromised.
Our discussion to this point has focused on the medically crucial considerations of contamination and infection. Yet there are other parallel concerns in the use of catheters and other therapeutic inserts, particularly those articles that are fitted closely into a very narrow preexisting bodily duct such as the male urethra.
Such concerns saliently include friction and pain. Urinary catheterization of male patients may be among the most greatly feared of routine medical procedures.
Although a portion of this response may arise from the special psychological considerations associated with the reproductive organs, nonetheless these organs are extremely sensitive. Insertion is often mechanically difficult and sometimes extremely painful.
There is accordingly an important need to reduce the mechanical friction of insertion, and with it a great deal of discomfort. In addition there is a need to desensitize the affected internal membranes to the residual trauma of insertion.